Limit-switch for hoisting-machines.



F. L. STONE.

LIMIT SWITCH FOR HOISTING MACHINES. APPLICATION map JULY 24.1915.

1,242,260.. Patented Oct. 9,1917.

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nventor Fred L. Stone,

F. L. STONE.

LIMIT SWITCH FOR HOISTENG MACPHNES. APPLlCATiON man JULY 24.1915.

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Application filed July at, 1915..

and its object is to provide improved limit switch for automatically cont; llin the speed or" the cage at each end o travel. The switch 1s designed for connection with a system of mine hoisting mechanism in which the cage slowed down before it arrives atthe lanol- 111g. in order to insure -that it shall stop accurately at said landing, and avoid all riskot overtraveh The invention involves the use of a traveling actuator geared to the hoisting mechanism so as to move syn= chronously therewith, and in one form is arranged to trip switches at each end of its travel and thereby first cut in resistance to slow down the hoisting motor and secend to stop it by opening the controlling circuits of the motor; In order to secure an easy and accurate adjustment of the time of tripping the switches, ll provide means for adjusting the positions of the switchesthemselves in a definite manner, and further provide on the traveling actuator a plurality of trips which are adjustable in such a manner that after each switch is adjusted in position to be engaged by its correspond ing trip, the tripping or the switch is hastened or retarded as desired by simply shifting the trip along a predetermined line on the actuator without necessitating any further adj u'stment of the switch itself. My

invention makes possible an accurate predetermination of the limits in which the hoist will operate and further provides an exceedingly simple arrangement whereby the hoist maybe adjusted to stop exactly at the place desired, this finer adjustment being also accurately predeterminable. I

In the accompanying drawings, Figure l is a front elevation of my improved limit switch, the cover being shown in section; Fig. is a plan view of the switch; Fig. 3 is across-section on the line 3'3, Fig. 1; Fig, 4 is a view of one of the snap switches "peciiication of Letters Patent.

Patented theft. 9, 1191?.

in. areas.

on a larger scale, and Fig. 5 is a perspective, view of one or the trips on the traveling actuator.

The mechanism is mounted on a suitable base plate 1 and is protected by a sheet cover 2, which has handles 3 and lugs a, the latter engaging with clamps 5 attached to the base plate. At each end of the base plate is a pedestal 6 in which is secured. one end of the stationary screw 7. An actuator is mounted on this screw, and comprises a hub 8 constituting a nut meshing with the screw, and a d 9 concentric with said hub and supported by arms 10.

At one end of the drum is a gear wheel ll concentric with the screw and provided with enshrouding flanges 12. An idle gear 13 v meshes withsaid gear wheel, fitting between the flanges 12. The idler can slide freely along shaft 14 supported at its ends by the pedestals 6 and parallel with the screw 7. The idler 13 also meshes with a long pinion 15 extending parallel with the screw 7 and journaled in bearings in the pedestals 6. The shaft 16 of this pinion is adapted to be connected in any suitable manner with a rotating element of the hoist, so that the pinion will rotate in synchronism therewith as the cage traverses the shaft; said pinion turning in one direction when the cage is descending, and in theother direction when it is rising. The rotation of the pinion is transmitted through the idler 13 to the gear 11 and the drum, which, by reason or" its screw-threaded hub, will fleet along'the stationary screw in one direction or the other, depending upon the direction of rotation of the hoisting mechanism. Adjustable tant ts 01' trips 17 are secured to the surface ofthefdrum 9. The preferred form of trip is shown in Fig. 5, where it is illustrated as having a foot 18 provided with a longitudinalgslot or sl0ts'19 to receive a clamping bolt 20:. In the drum are several holes 21, equally spaced apart and arranged preferably in a helical line, whose pitch agrees with that of the stationary screw 7. The result of this arrangement of theholes and the slots in the foot, is, that when a trip is adjusted angulai'lv around the drum, it will also be shifted axially.

on a guide or shifting the trips in the slots provided in the feet of the trips, a very minute and accurate adjustment can-be made. I i

The bed plate supports snap switches adapted to be operated by the trips 17. There are preferably two switches at each end of the travel of the drum along the screw; one on each side. They are mounted guides, preferably flat finished ways 22, 23 integral with the bed plate. Each switch has a base 241 which rests on said ways, and may be provided with a rib 25 to engage a longitudinal groove 26 in one of the ways. By means of a plurality of recesses in one of said ways, and a lock on the switch base, the switch can be adjusted along said ways. In the drawings, I have shown a screw 27 entering one of a series of screw-threaded holes 28 in the way 23. These recesses are spaced apart a distance equal to the pitch of the stationary screw 7 so that by shifting any switch from one recess to the next in succession the switch will be operated by its trip as before, with the exception that the time of tripping has been delayed or hastened as the case may be a period corresponding to a single revolution of the drum.

The snap switch may be of any preferred.

construction. The one shown is composed of two separate arms 29, 3O pivoted side by side on a pivot pin 31 carried in brackets 32 on the base 24:." A coiled spring 33 connects the two arms, one of which carries a contact 34 which cooperates with a fixed contact 35, mounted on a block 36 of insulating material secured to the base 24. This I arm 29 has a shoulder 37 which is engaged by a spring latch 38 when the contacts are closed. The arm 30 has a finger 39 which bears against the latch and forces it back to disengage the arm 29, when the arm 30 has been angularly moved through a given arc. This movement of the arm 30 puts a tension on the spring 33, so that the instant the latch releases the arm 29, the latter turns quickly and separates the contacts. The same snap action occurs in closing the switch, because the arm 29 has another shoulder 37 which the latch engages when the switch is open; only to be released by the return of the arm 30' to its original position.

The arm 30 carries two lugs 40, 41, the former being engaged by a trip 17 when the switch is to be opened, and the latter by the same trip-on a reversal of rotation of the drum, for the purpose of closing the switch.

The switches are adjusted along the ways i to positions whichj.- will insure the proper introduction or withdrawal of resistance from the circuit ofthe hoisting motor by one pair of switches, and also the opening or 3 closing of said circuit by the other pair.

A finer adjustment of the times of such operation is secured by shifting the trips along the helical line of holes in the drum. It

' will be noticed that by loosening the bolts justable along the helical line of the same ,1

pitch as the stationary screw, it is unnecessary to adjust the switch corresponding to the trip when the trip is adjusted since the trip in the adjusted position will engage the switch exactly as before except that the time of engagement has been changed. If the length of the screw is one and a half feet,

its pitch one-half inch, and the diameter of the drum one foot, then in traversing from one end of the screw to the other the drum will make 36 revolutions and a given point on the drum will have a travel of 113 feet. A very long travel is thus secured in a very compact device. If the shaft is say 1000 feet deep, this gives more than a foot of travel of the drum for every ten feet of travel of the cage, permitting very close adjustment of the points at which the slowing down and stopping of the motor are to be efiected.

Let it be supposed that it is desired to change the hoisting limits so that the hoist will stop at the 800 foot level instead of at the 1000 foot level, thereby necessitating an adjustment of 200 feet in the hoisting limits. This would mean that either the switches which govern the lower limits would have to be moved nearer the switches which govern the upper limits and the trips then accurately adjusted, or the trips themselves be adjusted to take care of the whole change. For such a change, however, it

would be preferable to move the final limit switch along the ways so as to take the greater part of the change. Thus, the distance between any two of the recesses on the ways corresponds, in the example selected for illustration, to a travel of about 27.8 feet for the hoist. Therefore the lower limit switch should be moved seven recesses nearer the upper limit switches, thus cansin the hoist to stop at about the 805.5 foot level. Now, since every foot on the helical line on the drum corresponds roughly to about nine feet of travel of the hoist, the operator can almost by sight determine the proper place to which the trip shall be shifted to cause the hoist to be stopped at the 800 foot level. Having thus determined approximately the proper position for the trip, it is only necessary for the operator to make a trial run and then shift the trips in the slots of the feet to exactly the proper position. The slow down switch, is of patent statutes, l have described the printill ciple of operation of my invention, together with the apparatus which it now consider to represent the (best embodiment thereof; but l desire to have it understood that toe apparatus shown is only illustrative, and that the invention can be carried out by other means, the scope or my invention oeing set forth in the annexed claims,

What I claim as new and desire to secure by Letters Patent of the United l, A limit switch for motor 'riven hoists comprising a plurality of switches, a t'atable and longitudinally movable geared to the hoist, and a plurality mounted on said drum adjustable L on in various positions so as to eng 3 switches and operate the same each o-= sition,

2. A limit switch for motor driv comprising a screw, a rotatable drui able longitudinally with reference thereof and geared to the hoist, and plurality of trips for operating the switches, on said drum and adjustable in various pa: sitions along a helical line oi? the same pitch as the screw so as to engage the switches and operate the same in each position 3. A limit switch for motor driven hoists comprising a drum movable longitudinally andrrotatably in geared relation with the movement of the hoist, trips'on said drum, means for adjusting the trips simultaneously angularly and longitudinally on the 1 and a plurality of switches operated by saio trips. Y

1-. A limit switch for motor driven hoists and rotatably in geared relation a movement of the hoist, trips on said orum, means for adjusting the trips thereon along a helical line and a plurality of switches operated by said trips. 0 o

5. A limit switch for motor driven hoists comprising a stationary screw, a drum mov-= able longitudinally thereof, an elongated pinion driven by the hoist and geared to the drum, trips on said drum, means for ads justing the trips along a helical line of the same pitch as the screw, and a plurality of switches actuated by said trips.

6. A limit switch for motor driven hoists comprisin a screw, a rotatable drum movable longitudinally with reference thereto, a pinion driven by the hoist and geared to the drum, trips on said drum and a pluprising a stationary screw, shai plurality of recesses spaced apart the p on the movement of thehoist, movable rotatably rality of switches adjustable. longitudinally of the drum in a plurality of predetermined positions actuated by said trips, I

7. A limit switch for electric motors, comprising a stationary screw, a drum having a screw-threaded hub engaging with said screw, a long pinion driven by the motor, intermediate gearing between said p' .l a, and drum, a plurality of trips having slotted feet, means inserted through the slots in the feet of the trips and arranged no 'he drum along a helical line of the same as the stationary screw for securing the to the drum, and a plurality of si itches adapted to be actuated by w ti. I

u. A umn, switch ior e 60611.10 motors, co prising a stationary screw, a drum l. a screw threaded hub engaging 'v screw, a shrouded gear wheel on salt -r, 35

an idler gear meshing therewith, lo pinion meshing with said idler, trips drum, and a plurality of snap sw adapted be actuated by said trips,

9'. A switch for electric motors, ccznon pinion parallel therewith, a oh. ing a screw-threaded hub engagin said screw, a shrouded gear on said an idler gear free to slide and rotate shaft and meshing wit the shrouden and the pinion, trips on said drum, plurality of snap switches adapted actuated by said trips 10. A limit switch for electric motors, comprising a base plate having ways, stationary screw suppo ted above said base plate and parallel n said ways, a on said screw, means for causing the drum to rotate and fleet along said screw, and a ma plurality-oat snap switches adjustable along said ways and adapted to be actuated by said drum.

ll, A limit switch for electric hoists, com

prising a stationary screw, a plura switches mounted on waysparallel screw and adyustable along the ways i Y of the screw, a drum in geared relation with and longitudinally with respect to'the screw, and a plurality of trips adjustably mounted on the drum for engaging and operatingthe. switches in various positions,

12,?A limit switch for electric hoists comprising a stationary screw, a plurality of switches mounted on ways parallel with the screw and adjustable along the ways in a plurality of recesses spaced apart the pitch of the screw, a drum in geared relation with the movement of the hoist, movable; rota-tably and longitudinally with- .respect-to the screw, and a plurality of trips mounted on the drum and adjustablethereon alongfahelical line as the same pitch of the'screw 5 for engaging and operating the switches in by bolts passing through the holes in the various positions. drum and the slots in thefeet, whereby 13. A limit switch for electric motors, the trips may be adjusted simultaneously comprising a stationary screw, a drum hayangularly and axially on the drum along 5 ing a plurality of holes arranged on the the helical line, and a plurality of switches 15 drum surface in a helical line of the same operated by the trips. pitch as the screw, the said drum being mov- In witness whereof, I have hereunto set able longitudinally and rotatably with refmy hand this 22nd day of J uly,-19l5. erence to the screw and geared to the motor,

10 trips having slotted feet securedto the drum FRED L. STONE. 

